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Melissa Parade, Jonathan S. Matthis, Brett R. Fajen; Non-visual self-motion information influences the perception of object motion while walking. Journal of Vision 2011;11(11):898. doi: 10.1167/11.11.898.
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© 2015 Association for Research in Vision and Ophthalmology.
When people walk through environments containing moving objects, the self-motion and object-motion components of optic flow are additively combined. Detecting the information needed to select routes requires the visual system to recover the object-motion component by discounting the self-motion component. This experiment is part of a larger study in which we are systematically evaluating how visual and non-visual information about the direction and magnitude of self-motion contribute in recovering the object-motion component. In this particular study, we focused on the role of non-visual information about the direction of self-motion. The experiment consisted of two sessions and was conducted in an immersive virtual environment viewed through a head-mounted display. In Session A, subjects were instructed to walk along a straight path as an obstacle moved from right to left along a path that would intersect their future path. Within 1.6 s of moving, subjects judged whether they would pass to the left or right of the moving obstacle. Judgments in Session A were compared with judgments in Session B in which the conditions were identical except that non-visual self-motion information was manipulated. This was achieved by laterally displacing subjects in the virtual environment 0.4 m leftward for every 1.0 m of forward movement. Because the lateral shift manipulation was present on the majority (83%) of trials, the perceived direction of self-motion based on non-visual information was realigned. On the remaining 17% of trials in Session B, the lateral shift manipulation was removed. Conditions on such catch trials in Session B were identical to conditions in Session A except that the perceived direction of self-motion based on non-visual information was offset. For most but not all subjects (N = 16), judgments in Session B were influenced in a way that is consistent with the use of non-visual information about direction of self-motion.
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